If the dog continues to chew on electrical cords, you may not have to worry about it.
Seriously, that is VERY dangerous. It can kill a puppy.
So, you need to ONLY let the puppy have access to ANY dangerous area when you are paying attention and then you need to divert him to something appropriate. Saying EH! or NO! MINE! and then showing him something he can have and saying in an easier voice, Yours, and give it to him.
If necessary, keep a lead on the dog and do not allow him access to the cords, though it is best to teach him to not mess with the cords.
Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.